If you want it bad enough it will happen. Build one, get some friends to build cars and you will find a place to race them. Someone always has to be first.
You don't have to run against other HA/GR's to run an HA/GR. My other drag car is a Crosley wagon and I never run against any other Crosleys. Do what "64" sez, build one and run it against whatever is in the other lane. Maybe some other guys will get the "bug".